The cancer that took the life of former Toronto Mayor Rob Ford is incredibly rare and very difficult to treat.

Known as pleomorphic liposarcoma, it affects only a few dozen patients in Canada each year. But it’s particularly lethal because each cancer cell looks different from the others, and tumours tend to form in areas where they don’t trigger any immediate symptoms. By the time doctors find them and a diagnosis is given, the cancer has sometimes grown to the point where operations and traditional treatments can no longer help.

In the case of Ford, he underwent surgery, radiation and four rounds of chemotherapy after two tumours were discovered in his abdomen and buttocks in 2014. The treatments were successful in shrinking the growths, but last November doctors discovered his cancer had returned in the form of two new tumours on his bladder.

For now, scientists don’t know what causes pleomorphic liposarcoma. There is no evidence currently that links the disease to alcohol, tobacco, stress or even obesity. Advocates say that because of its rarity, pleomorphic liposarcoma is often neglected in terms of research and funding. If there’s any silver lining here at all, it may be that Ford’s battle could draw some much-needed attention to it.

For more information about pleomorphic liposarcoma, check out the video above.